FYI, Windows Update will automatically download and install Windows Defender definition updates once per day, if you want to download and install the antimalware and antispyware updates manually for the same in Windows 10 to deal with the latest hard to remove malware or because of internet connection issues or if Windows Update isn’t working for you, you can do that, here is how.
Download and installing Windows Defender Updates manually in Windows 10
1. First know, which version of Windows -32-bit or 64-bit -you’re using. For that, right click on ‘This PC’ and select ‘Properties’, the ‘System type’ field under ‘System’ will reveal whether you’re using 32-bit or 64-bit version of Windows 10.
2. Next, visit Microsoft Malware Protection Center get definitions page, and scroll down a bit and under ‘manually download latest updates’, depending on your Windows version, click on 32-bit or 64-bit or ARM link offered for Windows Defender in Windows 10 and 8.1
3. A file with name mpam-fe.exe will be downloaded to your computer. Run it after saving for Windows Defender definitions to be updated.